Causes a store to add the specified flag to the
flags set for the messages in the specified
sequence.
imap_streamAn IMAP stream returned by imap_open().
sequenceA sequence of message numbers. You can enumerate desired messages with the X,Y syntax, or retrieve all messages within an interval with the X:Y syntax
flagThe flags which you can set are \\Seen, \\Answered, \\Flagged, \\Deleted, and \\Draft as defined by RFC2060.
optionsA bit mask that may contain the single option:
ST_UID - The sequence argument contains UIDs instead of sequence numbers